Léon Bloy (born July 11, 1846, Périgueux, France—died November 2, 1917, Bourg-la-Reine) was a French novelist, critic, and polemicist, a fervent Roman Catholic convert who preached spiritual revival through suffering and poverty.

As spiritual mentor to a group of friends that included the writer Joris-Karl Huysmans, philosopher Jacques Maritain, and painter Georges Rouault, Bloy influenced their reconciliation with the Roman Catholic Church. Bloy’s works are extremely varied in form (novels, pamphlets, a Journal, exegesis), but they reveal a powerful unity of thought: through pain and destitution man is redeemed by the Holy Spirit and is awakened to the hidden language of the universe. His autobiographical novels, Le Désespéré (1886; The Desperate Man) and La Femme pauvre (1897; The Woman Who Was Poor), express his mystical conception of woman as the Holy Spirit and of love as a devouring fire. The eight volumes of his Journal (written 1892–1917; complete edition published 1939) reveal him as a crusader of the absolute, launching onslaughts against lukewarm Christians. Several volumes of his letters—to his wife and daughters, to Maritain, and to Pierre-Marie Termier, among others—have been published.